Electromagnetically operated mechanism using resonance effects



May 20, 1952 A. BEKEY 2,597,559

ELECTROMAGNETICALLY OPERATED MECHANISM USING RESONANCE EFFECTS Filed July 18. 1949 Z .4 53 INVENTOR. ANDEEW BE'KEY,

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Patented May 20, 1952 UNlTED STATES PATENT OFFICE ELECTROMAGNETICALLY PE R A T E D MECHANISM USING RESONANCE EF- FECTS 2 Claims.

This invention relates to electromagnetically operated mechanisms such as presses and the like wherein a plunger or armature carrying a tool is caused to operate on the work by an electromagnetic force.

In machinnes of this character control over the magnitudes of the current passing through the electromagnetic coil is desired. It is important that the current be small While the plunger is in inactive position for purposes of efficiency in operation and in design. It is, however, necessary to impart a suflicient momentum to the plunger so that it may satisfactorily do the work required.

It is one object of this invention to provide a circuit such that a very high current may act through a short time at an intermediate attracted position of the plunger or armature to produce the desired momentum and yet limit the current flowing at the extreme positions of the armature or plunger. In this manner, a small coil, consuming relatively little energy, may economically be used to achieve the desired results.

For this purpose, use is made of a series resonant circuit wherein resonance is achieved at a position intermediate the extremes of the path of the armature.

In machines of this character, it is important that the operation be limited to one cycle, such that safety with respect to the operator and the work is achieved. It is accordingly another object of this invention to insure against a recurrenceof the operating cycle of the machine. For this purpose, use is made of a novel circuit controlled by the position of the plunger or armature itself, and also an electromagnet or the like which prevents the circuit energizing the machine from being closed, a manual operation of a simple nature being necessary to recondition the circuit for operation.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be takenin a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is an elevation, partly in section showing an electromagnetically operated mechanism;

Fig. 2 is an elevation showing the cooperative relation between the moving portions of the electromagnetically operated mechanism with respect to a circuit controller mechanism;

Fig. 3 is a diagrammatic representation of this invention including the cooperating electric circuits;

Fig. 4 is a sectional view taken along the plane 44 of Fig. l.

A reciprocating machine such as a punch press In is shown, as in Figs. 1 and 2, provided with a plunger I I movable with respect to the work support II! forming a part of machine I0. A tool I2 and tool holder I3 are appropriately carried by the plunger II. The tool I2 is adapted in this instance to perform a punching operation on the work I4, as shown by the dotted line position in Fig. l.

The space in which the plunger I I is adapted to move is defined by appropriate guiding bores I5 and IS in the upper and lower bosses I1 and I8 projecting from the frame of the machine ID; the space is also defined by a coil I 9 substantially aligned with said bores I5 and I6 and occupying a position between the bosses I1 and I8, as well as by a stationary magnetic frame 20 formed of laminations and surrounding the coil I9.

The magnetic frame 20 is generally a hollow rectangle formed of laminations, there being an opening in the top of the frame 20 to permit movement of plunger I I. The coil I9 is disposed within frame 20 and in alignment with the top opening. Thus the plunger forms a part of the magnetic circuit for the coil I 9, the flux dividing through the ends of the frame 20. The plunger II has ahollow skirt portion 2| that is slotted at the bottom to permit relative movement with respect to the lower portion II of the frame 20. As shown most clearly in Fig. 4, the plunger II and coil 20 are generally of rectangular configuration.

In the position shown in Figs. 1 and 2, the coil I9 is not sufiiciently energized to pull the plunger or armature II downwardly, and the plunger II is held in its upper or inactive position by the aid of a compression spring 2 I.

The plunger II for this purpose carries a retainer 22 of inverted cup form, as by the aid of a bolt 23 appropriately secured to the top of plunger II. The spring 2I abuts the retainer 22 and also the upper boss I! of the machine I0. The spring 2I will therefore bias the plunger II to the inactive position illustrated.

When the coil I9 is suiliciently energized to attract the plunger I I, the stationary core or frame 3 28 will reduce the effective reluctance of the magnetic circuit in which plunger N forms a part, as the magnetic circuit approaches closed position corresponding to the attracted position of the armature or plunger II, indicated in dotted lines in Fig. 1.

As shown in Fig. 3, coil I9 is connected in series with a capacitor 24 and a variable resistor 25. Also in series with coil I9 is a pair of relatively movable contacts 26 and 21 forming a part of a circuit controller mechanism 28 to be hereinafter described.

In the inactive position of the circuit controller mechanism 28 as shown in Fig. 3, the contacts 26- and 21 are open, and thus the only path of current to the coil I9 is through a high impedance spark reducer consisting of a resistor 29 and a capacitor 30, the spark reducer being in parallel relationship with respect to the contacts 26 and 21.

The combined impedance of this paralleling circuit 29-33 of Fig. 3 is sufficiently high to prevent a large enough current from flowing in coil I9, such thatplunger or armature I I remains in the position shown in Figs. 1 and 2. The circuit may be traced as follows: terminal 3| of .a source of alternating current, variable resistor 25, capacitor 24, coil I9, terminal 32, capacitor 30, resistor 29, lead 65, terminal 33, lead 53, to terminal 34 connected to the other side of the source.

Should it be desired to operate the mechanism, contacts .26 and 21 are closed (as will be hereinafter described) .and the high impedance spark reducer 2930 is thereby shunted. The circuit for operation of the plunger ll may be traced as follows: terminal 3| of a source of alternating current, variable resistor 25, capacitor 24, coil I9, terminal 32, lead 66, contacts 26 and 21, lead 52, terminal 33, lead .53, and to terminal 34 connected to the other side of the source.

It is well known, that when an armature is in unattracted position, such as plunger II in Figs. 1 and 2, the inductance of the cooperating electromagnet coil, such as coil I9, is small. It necessarily follows that the inductive reactance due to this coil I9 is small, and thus the current is limited more directly by other circuit parameters.

The inductance will necessarily increase as the armature or plunger moves into coil I9, and

therefore the corresponding reactance increases.

It is desired that the current be small in the unattracted position of Figs. 1 and 2 in spite of a low value of inductance and inductive reactance of the coil I9. But it is furthermore desirable that large currents be obtained in order to impart suflicient momentum and energy to the moving plunger II when desired. For this purpose, capacitor 24 is inserted as heretofore described to limit the current passing through coil I9 when the plunger II is in unattracted position, corresponding to the instant when contacts 26 and 21 are moved into engagement. The capacitor 24 will provide a substantially constant capacitive reactance. The capacitor 24 is of such a magnitude that the capacitive reactance produced thereby is balanced by or balances the inductive reactance of the coil I9 at a particular intermediate position of the plunger I.. At this particular intermediate position of the plunger H (the inductance having increased as plunger I'I advanced) the series circuit becomes resonant, and as is well known, the current through coil I9 will be limited only by the variable resistor 25. In this manner a large current momentarily passes through coil I9, and the force acting on plunger II is of considerable magnitude. At this position of resonance the plunger II is greatly accelerated to achieve the desired momentum and energy necessary to operate on the work 14.

After the position of resonance has passed by continued movement of plunger I, the force acting on plunger I may decrease, but the plunger II is still accelerated. When the tool |2 carried by the plunger II has encountered the work I4, the position of resonance has passed and the current becomes limited by the effective reactance (inductive) of .the coil I9 and the capacitor 24.

The resistance of resistor 25 may be adjusted according to the amount of work required to be done.

The circuit controller mechanism 28 controlling contacts 26 and 21 includes a frame 35 suitably secured on a support, as by machine bolts 36 and 31 or the like. A resilient arm 38 insulatedly supported at its lower end on frame 35 carries contact 26, which contact is adapted to cooperate with contact 21. Contact 21 is carried by a support 39 which in turn is mounted on frame 35, but insulated therefrom.

Arm 38 is anchored at one end by the aid of insulation blocks 48 appropriately secured. to frame 35.

Springs 4| and 42 are each anchored at one end on frame 35 and their free ends are secured to opposite sides of the resilient arm 38. These springs 4| and 42 thus oppose each other and tend to maintain arm 38 in the, inactive position shown in Fig. 3 such that contacts 26 and 21 are out of engagement.

For moving arm 38 to close contacts 26 and 21 in order to initiate the operation of the machine III through energization of coil I9, a magnetic plunger 43 is mounted at the free end of arm 38. This plunger 43 is adapted to be attracted by an electromagnet coil '44.

In order to provide for the energizatlon of electromagnet coil 44, a remote control switch 45. preferably operated by a pedal 13, is adapted to connect electromagnet coil 44 to a source of electrical energy. The circuit for electromagnet coil 44 includes a pair of relatively movable contacts 46 and 41. Contact 46 is carried byarm 28, and contact 41 is insulatedly mounted, similar to arm 38, on frame 35.

In the inactive position shown in 3, contacts 46 and 41 are in engagement so that opera.- tion of the remote control switch '45 may operate coil 44 to attract armature 43 against the spring forces of springs 4| and 42, causing-contacts 26 and 21 to engage so that'coll I9 may-be appropriately energized to operate the plunger H.

The circuit for electromagnet coil 44 may be traced as follows: terminal 3|, lead 48, remote control switch 45, leads 49 and 50, coil -44, lead 5|, contacts 41 and-46, arm 38, lead 52, terminal 33, lead 53, and terminal 34.

It is desired that the plunger II be limited 'to one cycle for each operation of pedal 13. While it may conceivably be possible that remote control switch 45 may be released promptly to interrupt energizationof electromagnet coil-44 permitting springs 4| and 42 to return arm'38 to inactive position, it is apparent that this depends on quick coordinated action by the individual operator. For insuring against an unwanted repetition of the cycle, use is made of the motion of the plunger I I itself in order to open contacts 46 and 41 as well as contacts 26 and 21 to interrupt current flow to the coil l9, and also to insure against an energization of coil 44, regardless of the position of the remote control switch 45.

As is shown most clearly in Figs. 4 and 3, plunger H is provided with a cam surface 54 adapted to move a cam follower 55 when plunger H approaches the extreme attracted position. The cam follower 55 is guided for longitudinal movement by a cam follower guide 56 suitably mounted on frame 55. The cam follower 55 is further guided in a recess 51 provided in boss [1 of machine [9. One end of a light compression spring 58 abuts the cam follower guide 56 and at the other end attached to the cam follower 55 to urge it into engagement with cam surface 54.

The cam follower 55 is adapted to contact armature 43 to move arm 38 to separate both contacts 26 and 21 and contacts 46 and 41. This is accomplished by the cam follower 55 being given an abrupt longitudinal movement by a steep rise in the cam surface 54, spring 58 being sufiiciently light to permit the cam follower 55 to leave the cam surface 54. In this manner, energization of coil [9 is interrupted, and also the circuit for energization of electromagnet coil 44 is interrupted.

In order to insure against a subsequent undesired operation of electromagnet coil 44, should remote control switch 45 not be released as the plunger II is retracted by spring 2i (contacts 29 and 21 having been separated), an electromagnet coil 59 is adapted to attract armature 43 and insure against the return of arm 38 to close contacts 46 and 41.

As the cam follower 55 moves armature 43 to the left, contacts 59 and 6| are established. Con tact 60 is carried by arm 38 and contact 5| is insulatedly supported in a manner similar to that of contact 41.

Should the pedal 13 still be depressed, maintaining switch 45 closed, the closing of contacts 50 and 6| by cam follower 55 establishes a circuit for electromagnet coil 59 as follows: terminal SI, lead :29, switch 45, lead 49, lead 62, coil 59, lead 63, contacts 5| and 60, arm 55, lead 52, terminal 33, lead 53, and terminal 34. Thus, the cam follower having established indirectly the circuit for electromagnet coil 59, if switch 45 is still closed, electromagnet coil 44 is prevented from being energized since contacts 46 and 41 are held apart by electromagnet coil 59. Thus there is no danger of a repeated cycle for plunger H as long as switch 45 is maintained closed.

Should the switch 45 thereafter be released, the excitation to electromagnet coil 59 will be interrupted, and springs 41 and 42 will return arm 38 to the inactive position of Fig. 3. In this position, electromagnet coil 44 may again be operated by closing remote control switch 45, and another cycle may be instituted.

It is thus necessary to release switch 45 before another cycle may be instituted.

The inventor claims:

1. In an electromagnetically operated mechanism having a armature or the like movable between attracted and unattracted position: electromagnet coil means adapted to attract said armature; means yieldingly urging said armature to a definite unattracted position a capacitance in series with said electromagnet coil means and having a reactance equalled by that of said electromagnet coil means when said armature is intermediate attracted and unattracted position; circuit means connecting said electromagnet coil means and said capacitance to a source of electrical energy; a circuit controller mechanism interposed in said circuit means; spring means biasing said circuit controller to open position; means closing said circuit controller mechanism including a remote control switch; means operated by said armature for opening said circuit controller; and means responsive to operation of said circuit controller opening means and dependent upon the continued closing of said remote control switch for preventing the closing of said circuit controller.

2. In an electromagnetically operated mechanism having an armature or the like movable between attracted and unattracted position: electromagnet coil means adapted to attract said armature; a capacitance in series with said electromagnet coil means and having a reactance equalled by that of said electromagnet coil means when said armature is intermediate attracted and unattracted position; circuit means connecting said electromagnet coil means and said capacitance to a source of electrical energy; a circuit controller mechanism interposed in said circuit, said circuit controller mechanism having a pair of relatively movable cooperating contacts; a movable arm carrying one of said relatively movable contacts; spring means engaging said arm for biasing the said arm to contact opening position; means moving said arm into contact closing position including an electromagnet, a circuit therfor and a remote control switch; a member operated by said armature when said armature moves to attracted position moving said arm to contact opening position; and means operated by said member dependent upon the continued closing of said remote control switch preventing the closing of said contacts.

ANDREW BEKE'Y.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 956,312 Dogilbert Apr. 26, 1910 2,040,677 Suits May 12, 1936 2,364,420 Bloss Dec. 5, 1944 2,476,419 Koening July 19, 1949 2,495,598 Parker Jan. 24, 1950 FOREIGN PATENTS Number Country Date 379,711 Great Britain 1932 602,989 Germany Sept. 20, 1934 

